Today there are a variety of different digital audio formats to choose from. Enough to cause confusion amongst new users who wish to convert their CD library into digital form for easy listening on their computers or portable audio device such as the iPod. This guide is designed to help newer users on deciding on a format to rip his or her music to.
The first thing you should consider is what you need from an audio format. Compatibility? Quality? Playable on your portable device? There is no right or wrong answer on which format you should use. It's a personal choice and it depends on your needs.
There are two types of audio formats: lossy and lossless. Lossy formats throw out audio information when encoding to lower the file size of the song so no lossy format is technically CD quality. However, perceivable quality is more important and lossy formats can provide audio that is indistinguishable from the original CD. Lossless formats work like Zip files. It compresses your audio as much as it can without throwing out any audio information. When the losslessly compressed file is decompressed it will have the same quality it had before it was compressed. In other words, lossless formats retain the CD quality audio on your CDs. There is no quality loss.
The bit rate of a file is the data rate that the audio is compressed at. There is no clear answer to which is best, it all depends on your hearing. Do some comparison tests between the CD quality audio and encoded files at various bit rates and determine which sounds best to you. Bit rates are used in the following ways:
* CBR (constant bit rate) - The file is encoded using the same bit rate throughout the entire file.
* VBR (variable bit rate) - The bit rate changes throughout the file according to the complexity of the music to offer the best quality.
* ABR (average bit rate) - This is a simple VBR mode where the bit rate fluctuates through out the song and averages out to be a certain bit rate.
Now let's start reviewing the various audio formats.
MP3 is by far the most popular audio format in use today. It was the first lossy compression codec which means it is also the oldest lossy compression format. MP3 can achieve transparent, or indistinguishable from CD, quality at around 192kbps-256kbps to most people on most samples. The LAME encoder is highly recommended when encoding MP3s by the folks at Hydrogenaudio.org. It is the highest quality MP3 encoder available. If you are concerned about compatibility with software and portable audio players then this is the format to use.
AAC or Advanced Audio Coding, is a relatively new format. AAC has been made popular by Apple because of its integration into Apple's iTunes music software and its iPod portable audio player. At any bit rate, AAC should sound better than MP3. Likewise, a 128 kbps AAC file should sound better than a 128 kbps MP3 file. AAC is gaining popularity and so it is becoming compatible with more media players but currently the iPod is the only major portable audio device that can playback MPEG-4 AAC. Note that AAC is not owned by Apple. It is defined in the MPEG-4 standard which means any portable audio device has the capability to add support for the format. The iTunes Music Store uses AAC at 128kbps. However, the iTunes Music Store wraps the FairPlay DRM protection around the MPEG-4 AAC files it sells. FairPlay is proprietary to Apple and currently Apple does not license it to other companies so the iPod remains the only player to be able to play files bought from the iTunes Music Store. Any music ripped to AAC in iTunes does not have any DRM protection attached to it.
WMA is Microsoft's answer to MP3. Exclusive to the Windows platform, WMA offers better sounding files at lower bit rates but currently WMA is not the best audio format. Better tuned MP3 encoders, AAC, Ogg Vorbis, and MusePack all beat WMA's quality at 128kbps and above. This format is not supported by the iPod but iTunes does offer a feature to convert WMA files to AAC/MP3 files for playback on the iPod.
FLAC stands for Free Lossless Audio Codec which is exactly what it is. It is non-patented and open-source. It supports multiple computing platforms and is considered the best lossless codec available by many. Encoding and decoding are both fast, compression is good, and seeking throughout a file is also fast. Currently, iTunes and iPod do not support FLAC.
WAV is the main format used for raw and typically uncompressed audio. The usual bitstream encoding is the Pulse Code Modulation (PCM) format.Uncompressed WAV files are quite large in size, so, as file sharing over the Internet has become popular, the WAV format has declined in popularity. However, it is still a commonly used, relatively "pure", i.e. lossless, file type, suitable for retaining "first generation" archived files of high quality, or use on a system where high fidelity sound is required and disk space is not restricted.